Bill Evans played with Miles Davis for no more than a total of 8 months. Miles Davis was a genius before he met Bill Evans. Bill Evans was a good piano player who complemented Miles's playing style @ the time. Without Miles Davis there's no Bill Evans, John Coltrane, Wayne Shorter, Herbie Hancock, Philly Joe Jones, Paul Chambers, etc.
All of the players you mention would be remembered as greats with or without Miles Davis. Their playing might have been different, but Miles wouldn't have been Miles without them, either.
Calling Bill Evans a "good piano player" is like calling Feynman a "good physicist".
Even though I consider all of these musicians to be greater than Miles Davis, it was Miles Davis who, as a band leader, let these individual members not only play in his band, but also shine by letting each of them solo on pieces instead of just him.
No one person deserves the credit. Duke was groundbreaking, but even without him there would have still been Billy Strayhorn and Charles Mingus and Thad Jones pushing the same boundaries of group writing and harmony, to name just a few.
